US 6843365 B2
A narrow belt conveyor system including a plurality of narrow, continuous, spaced-apart belts adapted to receive an accessory such as a sorter, accumulator, diverter, and/or transfer between the belts. The conveyor system includes a pair of side frame members, each with an elongated track that slidingly receives the accessory so that it can be readily moved to selected locations along the length of the conveyor. A belt tensioning mechanism provides for independent tensioning of the conveyor belts. A belt guide track with a low friction insert supports the loaded belt, while the guide rollers engage the edges of the belts along their return runs.
1. A belt tensioner for a conveyor comprising two or more endless belts, the belt tensioner comprising:
an axle member mounted to the conveyor transversely to the belts;
the first bracket assembly for each belt pivotally mounted to the axle member;
a tensioning pulley associated with each belt mounted for rotation with respect to its associated first bracket assembly;
a second bracket assembly pivotally mounted to the axle member;
an actuator connected to the second bracket assembly for pivoting the second bracket assembly about the axle member; and
a lost motion connector connecting each first bracket assembly to the second bracket assembly,
whereby, when said second bracket assembly is pivoted by the actuator about the axle member in a direction to apply tension to the belts, each bracket is tensioned individually to approximately the same tension.
2. The belt tensioner of
3. The belt tensioner of
4. The belt tensioner of
This is a division of application Ser. No. 10/072,411, filed Feb. 8, 2002 now abandoned.
This application claims the benefit of the filing date of provisional application Ser. No. 60/267,864, filed Feb. 9, 2001.
The present invention relates to a material handling system and, more particularly, to a narrow belt conveyor system.
Narrow belt conveyor systems use multiple, continuously moving parallel belts for conveying flat-bottomed objects along straight runs. Narrow belt conveyor systems are often used in conjunction with accessories, such as sorters, transfers, accumulators and/or diverters, which are located between the several belts of the conveyor intermediate the ends thereof, to, e.g., change the direction of conveyed items, etc. Such sorters, accumulators, transfers, and diverters, which may be, e.g., powered rollers or wheels, are moved from a retracted position that is beneath the top surface of the conveyor belts, to an extended position above the top surface so that they can engage the underside of the conveyed items to effect a change of direction.
Narrow belt conveyors are popular because of their versatility. In particular, they are susceptible to modification in the placement of the sorters, accumulators, transfers, and/or diverters to suit the changing needs of the users.
However, such narrow belt conveyors also have limitations. For example, the movement of the sorters, accumulators, transfers, and/or diverters can often be time consuming and labor intensive. In addition, the narrow belts must also track accurately in order to avoid interference with the various sorters, accumulators, transfers, and/or diverters that have to fit therebetween. As can be readily appreciated, any structure that provides for tracking must also not promote any undue wear of the belts. Further, proper tensioning of the belts is needed to make sure that each of the belts are driven at the same speed. This has also proven difficult, particularly if the several belts vary in length due to, for example, unequal stretching of the belts over their service lives.
Accordingly, it is an object of the present invention to provide an improved narrow belt conveyor system.
More particularly, it is an object to provide such a narrow belt conveyor system that facilitates the easy relocation of accessories such as transfers, accumulators, sorters, and/or diverters along the length of the conveyor.
It is another object to provide such a conveyor system that has improved belt tracking while not promoting undue belt wear.
It is also an object of the present invention to provide a belt tensioning apparatus for a narrow belt conveyor system which tensions the several belts equally.
These objects, as well as others which will become apparent upon reference to the accompanying drawings and following detailed description, are provided by a narrow belt conveyor system in which the belts are supported between a pair of opposed, elongated side frame members that extend between the drive end and the return end of the conveyor system. An elongated track is associated and generally co-extensive with each side frame member, with each elongated track being adapted to slidingly receive a mounting member of an accessory, such as a sorter, accumulator, transfer, and/or diverter, so that the accessory can be moved along the track to the desired location intermediate drive end and the return end. In a preferred embodiment, the elongated track is generally U-shaped so as to form a channel adapted to receive a slide plate, the slide plate being mounted to the accessory. The side frames may also be provided with a plurality of opposed, spaced-apart mounting holes for mounting external conveyor accessories such as conveyor spurs, photo-eye brackets, and scanners.
The conveyor may also be provided with a belt guide track for each belt comprising an elongated base member which is secured to the frame of the conveyor, and an elongated insert adapted to be carried on the base member. The base member is made of a low friction material and has opposed side walls to prevent the belt from moving laterally with respect to the support.
Additionally, a belt guide may be provided for the return run of each belt which comprises pairs of first and second freely-rotating rollers secured to the conveyor system on the opposite sides of each belt so that the rollers engage the edges of the belt. In a preferred embodiment, the rollers may include a channel adapted to receive the edge of the belt. Further, each roller in the pair may be longitudinally spaced from the other along the length of the belt.
Further, a belt tensioner is provided that includes an axle member which is mounted to the conveyor system transversely to the belts. A bracket assembly is provided for each belt that is pivotally mounted to the axle. Each bracket assembly includes a tensioning pulley that is mounted with respect to the bracket. A second bracket assembly is provided that is pivotally mounted to the axle member. An actuator is connected to this second bracket member for pivoting the second bracket assembly about the axle member. Each first bracket assembly is connected to the second bracket assembly by a lost motion connector comprising at least one resilient member. Thus, when the second bracket assembly is pivoted in the direction to apply tension to the belts, each bracket is tensioned individually to approximately the same tension.
The conveyor system of the present invention can be made in practically any desired configuration by combining straight run units 10 (
Each of these units includes opposed side frame members 16, 18 that interconnect and support the various components in the unit, such as 90° transfer 20 (
In keeping with one aspect of the present invention, the side frames 16, 18 have an elongated U-shaped track or channel 24 (best seen in
Each side frame 16, 18 also includes a plurality of mounting holes spaced at uniform intervals to facilitate mounting external conveyor accessories, such as conveyor spurs, photo-eye brackets, and scanners thereto.
In keeping with another aspect of the present invention, an improved belt guide track 28 (
While the track 28 described above guides and supports the loaded belt 15 on the exposed or top side of the sorter, on the return side, or under-side of the belt generally only directional guidance is needed, as no vertical load is supported by the belts.
Accordingly, in keeping with a further aspect of the present invention, pairs of freely-rotating side rollers 46 (best seen in
Belt tensioners are used in conveyor systems to insure that there is sufficient tension on the belt so that it does not slip when being engaged by the drive pulley. Belt tensioning is complicated in a narrow belt conveyor because slight variations in the lengths of the different belts can result in different tensions on the individual belts during the operation of the conveyor.
Accordingly, in a further aspect of the present invention (best seen in FIGS. 11-15), a plurality of freely-rotating tensioning sheaves or pulleys 52 are provided, one for each belt 15, with each pulley 52 being part of an assembly 54 that is pivotally mounted for rotation about a common axis 56. Each tensioning assembly 54 is mounted independently to the common axis 56 and is operatively connected to a pneumatic drive 58 comprising two pistons, with the pistons rotating the pulley assemblies 54 about the axis 56 to place tension on the belts 15 that are trained about the pulleys 52.
Each belt 15 has its own tensioning sheave or pulley 52 (as best seen in FIG. 14), with each pulley being supported between a pair of generally triangularly-shaped plates 62 to form a tensioning pulley assembly 54. The tensioning pulley 52 of each assembly 54 is supported adjacent one end of the hypotenuse of the triangle and the opposite end of the hypotenuse is supported for rotational movement about a cylindrical bar that forms the common axis 56 that is carried between the opposing side frame members 63 by brackets 64. The brackets 64 are secured to their respective side frames 63 by bolts 66. Each pair of triangularly-shaped plates 62 also includes a spacer bar 68 (
Two generally L-shaped drive plates 70 are also mounted on one end for rotation motion about the cylindrical bar 56, the two drive plates 70 being joined to one and other by a piece of elongated bar stock 72 so that they move in tandem about the cylindrical bar. The cylindrical bar 56 also supports nylon washers (not shown) between adjacent tensioning units 54 and drive plates 70. The second end of each drive plate 70 is pivotally connected to a piston rod 74 which is linearly moved by an associated cylinder 76, each cylinder 76 being pivotally mounted to the frame at 78. As will be described in greater detail below, the drive plates 70 are also operatively connected to the tensioning pulley units 54 so that tension can be applied to or released from the conveyor belts 15 through actuation of the cylinder 76/piston rod 74.
In accordance with this aspect of the invention, the four tensioning pulley units 54 are ganged together to provide for their movement in unison to tension the belts 15. However, each tensioning unit 54 includes a “lost motion” connector so that it is capable of a certain amount of tensioning movement independent from each of the other units 54. This accommodates for potential differences in the lengths of the several belts 15 comprising the conveyor system.
To this end, each of the mounting plates 62 in each tensioning unit is attached to the bar stock 72 that connects the two drive plates 70 to each other by a “lost motion” connection including a pair of springs 80. Each tensioning unit 54 has a short piece of bar stock 82 (best seen in
Thus, with reference to
Thus, a narrow belt conveyor has been provided that meets all the objects of the present invention. While the invention has been described in terms of certain specific embodiments, there is no intent to limit the invention to the same. Instead, the invention is defined by the following claims.